1. Field of the Invention
The present invention relates to image forming apparatuses such as copying machines, facsimiles, etc., that form images on sheets of paper.
2. Description of the Related Art
Conventionally, an image reading apparatus is known in which, when installing an image reading apparatus in an automobile and carrying out image reading while moving, at the time that a vibration sensor detects excessive vibrations such as when traveling on a bad road, etc., the image reading is suspended and the original document is transported in the reverse direction, and the reading out is restarted after vibrations are no longer detected (for example, Japanese Unexamined Patent Application Publication No. Hei 11-284801).
In recent years, users of image forming apparatuses are asking for high image quality, and even image forming apparatuses are moving in the direction of outputting images with a high image quality.
It is known that in image forming apparatuses outputting images with such high image quality, even very small vibrations such as those during attaching or detaching the sheet supply trays are likely to cause abnormalities in the reading of images from the original document, and the quality is likely to get deteriorated.
The invention disclosed in Japanese Unexamined Patent Application Publication No. Hei 11-284801 has the purpose of providing an image reading apparatus in which there is no image deterioration even when vibrations stronger than a presumed strength are generated while the image reading apparatus is installed in an automobile and the automobile is traveling, and in order to achieve this purpose, a vibration sensor is installed, the image reading is suspended and the original document is transported in the reverse direction at the time that said vibration sensor detects excessive vibration, and the reading out is restarted after vibrations are no longer detected.
Therefore, for example, it is possible that small vibrations such as those described above may not be detected by a vibration sensor whose purpose is to detect vibrations above a certain strength that are presumed to be generated while traveling on a bad road, and there was the problem that the output image quality decreased consequently in an image forming apparatus having such an image reading apparatus.
In addition, since the vibrations during traveling include vibration components in multiple directions, although it is necessary to detect vibrations with components in multiple directions in order to counter such vibrations, there is the problem that, in general, a vibration sensor that can detect vibrations in multiple directions is costly and hence increases the cost of the image forming apparatus.
The present invention is made in view of the above problems, and the purpose of the present invention is to provide an image forming apparatus that is low in cost and that does not cause decrease in the quality of the output image even when there are small vibrations at the time of attaching or detaching the sheet supply trays.